Underground salt caverns are used globally for large-scale energy storage. In the thinly bedded rock salt in China, two butted-well horizontal (TWH) caverns, as alternatives for energy storage, are regarded as having better suitability and economy than vertical caverns. However, understandings of the cavern shape development and control methods of TWH-caverns remain insufficient. To overcome these shortcomings with respect to TWH-caverns, we conducted physical simulations of TWH-cavern construction using a high strength steel mold and molded large rock salt specimens. We established a platform for physical simulation of TWH-cavern water-solution construction using the large molded rock salt specimens, so that the construction process is visible and easily observed. Six groups of physical simulations of TWH-cavern construction were designed and implemented. The variables which affect the cavern outline expansion were investigated and compared, including water injection rate, transferring of injection well, oil blanket, and retreating position of the water outlet. Finally the expansion rules of the cavern outline, and different effects when injecting from an inclined well vs. From a vertical well were explored, as well as an attempt of retreating water outlet. This study provides significant guidance for constructing horizontal caverns for energy storage in thinly bedded rock salt. (C) 2019 Elsevier Ltd. All rights reserved.